Lubricants containing amine salts



United States Patent 3,143,506 LUBRICANTS CONTAINING AMINE SALTS Elmer E. Schalienherg, Beacon, and Roger G. Lacoste, Hopewell Junction, N.Y., assignors to Texaco Inc, New York, N.Y., a corporation of Delaware No Drawing. Filed June 20, 1960, Ser. No. 37,090 4 Claims. (Cl. 25232.7)

This invention relates to lubricant compositions containing novel ashless detergents. More particularly, it relates to lubricants containing amine salts of hydrocarbyl thiophosphonic acids as detergents.

Our commonly-assigned copending application Serial No, 37,092 filed of even date, discloses novel amine salts of hydrocarbon thiophosphonic acids. The subject invention is concerned with the use of these novel amine salts as lubricating oil additives.

The lubricant compositions of this invention comprise a lubricating oil and an amine salt having one of the following formulae:

wherein R is a hydrocarbyl radical, R is an aliphatic hydrocarbyl radical containing 1-24 carbon atoms and preferably 5=22 carbon atoms, and R is a divalent aliphatic hydrocarbyl radical containing 21() carbon atoms and n is an integer having a value of l8. The acid amine salt is present in the lubricating oil in a concentration sufiicient to impart detergent properties to the lubricating oil. The acid amine salt concentration is usually between 0.2 and 10.0 weight percent.

The amine salts employed as ashless detergent additives in the lubricant compositions of this invention are simply prepared by reacting a hydrocarbyl thiophosphonic acid, obtained by hydrolysis of a hydrocarbon-P 5 reaction product, with an amine and heating under reflux for a period of time ranging from 0.5 to 2 hours. The reaction mixture is then blown with nitrogen at a temperature between 90 and 220 C. until the product is dried and free of unreacted amine. The acid amine salt of the structure shown above is obtained on cooling the reaction product.

The hydrocarbyl thiophosphonic acid employed in preparing the amine salt employed as a lubricant additive has the formula:

s Ri o 11 wherein R is a hydrocarbyl radical which may be aromatic, aliphatic or cycloaliphatic in nature and which usually contains 12 or more carbon atoms. The R radical in this formula is advantageously a polyolefin radical such as polyisobutylene or polypropylene having an average molecular weight between 400 and 5000 since such materials are the preferred materials for reaction with P 8 The hydrocarbyl thiophosphonic acids of the above formula are prepared by reaction of P 8 with a hydrocarbon at an elevated temperature of about 100320 C. in anon-oxidizing atmosphere followed by hydrolysis of the resulting product with steam at a temperature between about 100 and 260 C. Steam treatment of the P S hydrocarbon reaction product results in its hydrolysis to form inorganic phosphorus acids and a hydrocarbyl thiophosphonic acid of the structure shown above. The inorganic phosphorus acids are advantageously removed from the hydrolyzed reaction product prior to reaction with amine to form the novel amine salts of hydrocarbyl 3,143,505 Fatented Aug. 4, 1964 thiophosphonic acids. Removal of the inorganic phosphorus acids from the hydrolyzed product can be effected by the procedures disclosed in commonly-assigned copending applications Serial Nos. 750,874, now US. Patent 2,987,512, filed July 25, 1958 and 763,812, now US. Patent 2,951,835, filed September 29, 1958 by H. D. Kluge, and J. W. Wisuer, Jr., and R. G. Lacoste wherein removal is elfected by contact with synthetic hydrous alkaline earth metal silicates and synthetic hydrous alkali metal silicates, respectively. Inorganic phosphorus acids can also be removed by extraction with anhydrous methanol as disclosed in another commonly-assigned copending application Serial No. 841,668, filed September 23, 1959 by H. D. Kluge and R. G. Lacoste.

Monoamines employed in the formation of the novel amine salts of hydrocarbon thiophosphonic acids are represented by the following general formula: RNH wherein R is an aliphatic hydrocarbyl radical containing 1-24 carbon atoms and is preferably an aliphatic hydrocarbyl radical containing 5-20 carbon atoms. Examples of effective amines are ethylamine, isopropylamine, n-propylamine, Z-ethylhexylamine, n-amylamine, t-octylamine, laurylamine and mixtures of primary aliphatic amines such as commercially available mixtures of t-alkyl primary amines. Primene 81-R is a mixture of branched chain t-alkyl primary amines wherein the t-allryl group contains 11-14 carbon atoms and Primene JM-T is a mixture of t-alkyl primary amines wherein the t-alkyl groups contain 18-22 carbon atoms.

Alkylene polyamines containing 2 primary amino groups are represented by the formula:

wherein R" is a divalent aliphatic hydrocarbyl radical containing 2-10 carbon atoms and n is an integer having a value of l-8. Examples of effective polyamines are ethylenediamine, 1, 2-propylenediamine, 1,3-propylenediamine, LZ-butylenediamine, 1,6-hexylenediamine, 1,8- octylenediamine, 1,4-butylenediamine, 1,3-diaminobutane, pentaethylenehexamine, tetraethylenepentamine, triethylenetetramine, tripropylenetetramine, tetrapropylenepentamine, hexapropyleneheptamine, and diethylenetriamine.

Acid amine salts effective as lubricating oil detergents are illustrated by the following: The ethylenediamine salt of a polybutene (average molecular weight 780) thiophosphonic acid containing 2 mols of acid per mol of diamine; the diethylenetriamine salt of polybutene (average molecular weight 700) thiophosphonic acid containig 2 mols of acid per mol of amine; the tetraethylenepentamine salt of polybutene (average molecular weight 780) thiophosphonic acid containing 2 mols of acid per mol of amine; the tetraethylenepentamine salt of polybutene (average molecular weight 780) thiophosphonic acid containing 2 mols of acid per mol of amine; the pentamethylenehexamine salt of polybutene (average molecular weight 780) thiophosphonic acid containing 2 mols of acid per mol of amine; the Z-ethylhexylamine salt of polybutene (average molecular weight 780) thiophosphonic acid containing acid and amine in a mol ratio of 1:1; the cyclohexylamine salt of polybutene (average molecular weight 780) thiophosphonic acid containing acid and amine in a mol ratio of 1:1, the t-butylamine salt of polybutene (average molecular weight 780) thiophosphonic acid containing acid and amine in a mol ratio of 1:1; the salt of mixed t-alkyl primary amines containing 1114 carbon atoms (Primene 8l-R) salt of a polybutene (average molecular weight 1200) thiophosphonic acid containing amine and acid in a mol ratio of 1:1; the salt of a mixed t-alkyl primary amine containing 17-22 carbon atoms (Primene ]MT) and polypropylene (average molecular weight 900) thiophosphonic acid in a mol ratio of acid to amine of 1:1.

The hydrocarbon mineral oils usable in this invention can be paraflin base, naphthene base or mixed parafiinnaphthene base distillate or residual oils. Paraffin base distillate lubricating oil fractions are used in the formulation of premium grade motor oils such as are contemplated in this invention. The lubricating base generally has been subjected to solvent refining to improve its lubricity and viscosity temperature relationship as well as solvent dewaxing to remove waxy components and improve the pour of the oil. Broadly speaking, mineral lubricating oils having an SUS viscosity at 100 F. between 50 and 1000 may be used in the formulation of the improved lubricants of this invention but usually the viscosity range falls between 70 and 300 at 100 F.

The mineral lubricating oils containing amine salts of hydrocarbyl thiophosphonic acids usually contain other additives designed to impart other desirable properties thereto. For example, VI improvers such as the polymethacrylates are normally included therein as are corrosion inhibitors and other dispersants.

A Widely used VI improver is a polymethacrylate of the general formula:

wherein R is an aliphatic radical.

The most commonly used supplementary detergent is an alkaline earth metal alkyl phenolate. These products are well known detergent additives and do not require detailed description.

The most commonly used inhibitor and antioxidant is a divalent metal alkyl dithiophosphate resulting from the neutralization of a P S -alcohol reaction product with a divalent metal or divalent metal oxide. Barium and zinc alkyl dithiophosphates are the most widely used additives.

Synthetic lubricating bases of the ester or ether type may also be used as the lubricating oil. High molecular weight, high boiling liquid aliphatic dicarboxylic acid esters possess excellent viscosity-temperature relationships and lubricating properties and are finding ever-increasing utilization in lubricating oils adapted for high and low temperature lubrication; esters of this type are used in the formulation of jet engine oils. Examples of this class of synthetic lubricating bases are the diesters of acids such as sebacic, adipic, azelaic, alkenyl succinic, etc.; specific examples of these diesters are di-Z-ethylhexyl sebacate, di-2-ethylhexyl azelate, di-Z-ethylhexyl adipate, di-n-amyl sebacate, di-2-ethylhexyl n-dodecyl succinate, di-Z-ethoxyethyl sebacate, di-2'-methoxy-2-ethoxyethyl sebacate (the methyl Carbitol diester), di-2'-ethyl-2-n-butoxyethyl sebacate (the Z-ethylbutyl Cellosolve diester), di-Z-n-butoxyethyl azelate (the n-butyl Cellosolve diester) and di-2'-nbutoxy-Z-ethoxyethyl-n-octyl succinate (the n-butyl Carbitol diester) Polyester lubricants formed by a reaction of an aliphatic dicarboxylic acid of the type previously described, a dihydroxy compound and a monofunctional aliphatic monohydroxy alcohol or an aliphatic monocarboxylic acid in specified mol ratios are also employed as the synthetic lubricating base in the compositions of this invention; polyesters of this type are described in U.S. 2,628,974. Polyesters formed by reaction of a mixture containing specified amounts of heptanediol, sebacic acid and Z-ethylhexanol and of a mixture containing adipic acid, diethylene glycol and 2-ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.

Polyalkylene ethers as illustrated by polyglycols are also used as the lubricating base in the compositions of this invention. Polyethylene glycol, polypropylene glycol, polybutylene glycols and mixed polyethylene-polypropylene glycols are examples of this class of synthetic lubricating bases.

The sulfur analogs of the above-described diesters, polyesters and polyalkylene ethers are also used in the formulation of the lubricating compositions of this invention. Dithioesters are exemplified by di-Z-ethylhexyl thiosebacate and di-n-octyl thioadipate; polyethylene thioglycol is an example of the sulfur analogs of the polyalkylene glycols; sulfur analogs of polyesters are exemplified by the reaction product of adipic acid, thioglycol and Z-ethylhexyl mercaptan.

The acid amine salt of the hydrocarbyl thiophosphonic acid is present in the lubricating oil in concentrations sufiicient to impart dispersant properties thereto. In concentrates used to formulate finished lubricants the acid amine salt concentration can be as high as 50%. In finished lubricants, the concentration of amine salt is between 0.2 and 10.0 weight percent, with concentrations between 1.0 and 5.0 weight percent normally being employed.

An SAE 10W-30 motor oil with an amine salt of a hydrocarbyl thiophosphonic acid was formulated as follows:

TABLE I Wt. Percent Concentration Refined parafiinic distillate oil 88.2 Ethylenediamine salt of polybutene (Av. Mol. Wt.

780) thiophosphonic acid 3.75 Barium C alkylphenolate 2.45

Zinc isopropyl methylisobutyl carbinyl dithiophosphate Mineral oil concentrate containing 27 wt. percent of a copolymer of of mixed methacrylate alkyl esters in which the alkyl groups range from butyl to stearyl and 10% of vinyl pyrrolidone 5.0 Dimethyl silicone anti-foam concentrate ppm 150 Inspection tests on this SAE 10W-30 grade motor oil were obtained with the following results:

Gravity, API 29.8

Flash, COC F 425 Viscosity, SSU at 0 F. (extrap) 11,000

This SAE 10W-30 oil was evaluated in both the Chevrolet SII Test and in the extended version of the Chevrolet L-4 Test, which has a CRC designation of L-4-1252.

The Chevrolet S-II Test is conducted under conditions simulating low temperature operation wherein deposit formation is most pronounced. The merit system of evaluation involves visual examination of the engine parts after disassembly and their rating according to deposits by comparison with standards which have assigned ratings. Individual parts, e.g. pistons, are rated in the Chevrolet SII Test on the system wherein a 10 rating designates a clean part, that is, without deposits, and a rating of 0 represents the worst condition. Total engine varnish and total engine sludge are rated on a system wherein 50 designates the absence of deposits and 0 indicates the worst condition.

The Chevrolet L-4 Test is used to evaluate the performance of a motor oil under high temperature conditions where Wear and corrosion are problems.

In the extended Chevrolet L-4 Test, which in this instance was of 108 hours duration, the individual pistons are also rated by a merit system wherein l0 denotes a clean piston, with 0 designating the worst condition; the total engine deposits are evaluated on a system wherein designates a perfectly clean engine and 0 the worst condition. In the following table are shown the evaluation of the above SAE lOW-SO motor oil containing an ethylenediamine salt of polybutene thiophosphonic acid as a dispersant.

TABLE 11 Engine Tests on SAE W-3O Motor Oil Containing Ethylenedz'amine Salt of Polybzttene Thiophosphonic Acid Chevrolet S-II Test: Ratings Piston varnish 8.0 Total engine varnish 43.0

The above data indicate that a high quality SAE l0W-30 grade motor oil was prepared employing an ethylenediamine polybutene thiophosphonic acid salt as a dispersant.

In Table III the effectiveness of the same ethylenediamine salt of polybutene thiophosphonic acid was demonstrated in a base oil comprising 95.38% of a refined parafiim'c distillate oil, 0.62% Zinc isopropyl methylisobutyl carbinyl dithiophosphate and 4.0% of a mineral oil concentrate of mixed methacrylate alkyl ester polymers and containing 150 ppm. of dimethyl silicone anti-foam concentrate. The effectiveness was demonstrated in the low temperature Chevrolet S-II Test described previously employing a regular leaded gasoline as a fuel.

TABLE III Efiectiveness of Acid-Amine Salts of Hydrocarbyl T hi0- phosphonic Acids as Detergent Additives The data in the above table show the effectiveness of acid-amine salts of hydrocarbyl thiophosphonic acids in improving the dispersancy of the reference oil. The improvements in piston varnish rating and over-all engine deposit ratings efiected solely by the addition of the ethylenediamine salt of polybutene thiophosphonic acid are particularly outstanding.

The action of n-butylamine salt of polybutene (average molecular weight 780) thiophosphonic acid as a dispersant was shown by the improvement effected in the engine sludge rating of the Chevrolet S-II Test employing the same base oil and fuel employed in the data presented in Table III. The addition of 3 wt. percent of the butylamine salt of polybutene thiophosphonic acid to the afore-described base oil raised the engine sludge rating from 41 to 48 thereby clearly demonstrating the effectiveness of the acid salts of monoamines and hydrocarbyl thiophosphonic acids as lubricating oil dispersants.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A lubricating composition comprising lubricating oil as the major component and a polyamine salt of a hydrocarbyl thiophosphonic acid in an amount sufiicient to impart detergent properties through said polyamine salt having the general formula where R is a hydrocarbyl radical containing at least 12 carbon atoms, R" is a divalent aliphatic hydrocarbyl radical containing 2 to 10 carbon atoms and n is an integer having a value of 1 to 8.

2. A lubricating composition as described in claim 1 in which the amine salt is present in a concentration between 02 and 10.0 weight percent.

3. A lubricating composition as described in claim 1 in which said lubricating oil is a mineral lubricating oil having an SUS viscosity at 100 F. between 50 and 100.

4. A lubricating composition as described in claim 1 containing 0.2 to 10.0 Weight percent of the acid salt of ethylenediamine and polybutene thiophosphonic acid said polybutene having an average molecular weight between 400 and 5,000.

References Cited in the file of this patent UNITED STATES PATENTS 2,636,858 Jones et a1. Apr. 28, 1953 2,806,022 Sabol Sept. 10, 1957 2,809,934 Alford et a1. Oct. 15, 1957 2,882,228 Watson et a1 Apr. 14, 1959 2,900,376 Sabol et a1 Aug. 18, 1959 

1. A LUBRICATING COMPOSITON COMPRISING LUBRICATING OIL AS THE MAJOR COMPONENT OF A POLYAMINE SALT OF A HYDROCARBYL THIOPHOSPHONIC ACID IN AN AMOUNT SUFFICIENT TO IMPART DETERGENT PROPERTIES THROUGH SAID POLYAMINE SALT HAVING THE GENERAL FORMULA 